Swivel chair



FIG. 1 is a perspective front elevational view of a swivel chair showing the new design;

FIG. 2 is a perspective side elevational view of the swivel chair as seen from the right-hand side of FIG. 1;

FIG. 3 is a perspective plan view of the swivel chair; and

FIG. 4 is a perspective rear elevational view of the swivel chair. 

The ornamental design for a swivel chair, substantially as shown. 